1. Technical Field
This application relates to a percutaneous puncture system and more particularly to a percutaneous puncture system and method for creating a tract for nephrostomy tube creation.
2. Background of Related Art
Nephrostomy is the creation of a communication between the skin and kidney to provide for nephrostomy tube insertion. The objective in nephrostomy tube creation is to have the wire from outside the flank directed down the ureter to provide therapeutic drainage of an obstructed system. This allows for subsequent dilation of the tract, such as by a nephrostomy dilating balloon, between the kidney and the skin over a wire that extends down the ureter. The catheter and tract can also be used to facilitate stenting of a narrowed ureter or removal or treatment of stones obstructing the ureter. Current nephrostomy tube creation is dependent on x-ray exposure to guide the physician where to locate the nephrostomy puncture wire tract.
There are currently two widely used techniques for nephrostomy tube creation. One technique utilizes an antegrade approach. The antegrade approach holds increased bleeding risk due to the puncture needle puncturing the interlobar arteries as it passes into the collecting system. This antegrade approach is also skill intensive because it requires advancing from the flank to an “unknown” calyx. In fact, studies have shown that recent urology resident graduates often do not continue to perform the antegrade nephrostomy technique after graduating due to difficulty of this procedure. The procedure also requires a relatively large amount of radiation exposure.
The other technique commonly utilized is the Lawson technique. This technique is used to create a nephrostomy tract in a retrograde fashion. The Lawson technique is performed under fluoroscopy utilizing a deflecting wire inside a ureteric catheter to select the renal calyx to be entered. That is, fluoroscopy is used to identify the renal calyx for nephrostomy access. The Lawson technique is described for example in Smith's Textbook of Urology, 2007, BC Decker Inc., “Retrograde Access” by Dennis H. Hosking and is commercially available by Cook Urological, Inc. as the “Lawson Retrograde Nephrostomy Wire Puncture Set.”
In the Lawson technique, a stainless steel 145 cm long guidewire (0.038 inches in diameter) having a 3 cm flexible tip is passed retrograde up the ureter into the renal pelvis under fluoroscopy. A 7 Fr catheter is passed over the guidewire into the renal pelvis and the guidewire is removed. A J-tipped wire in certain instances might be used to facilitate passage past an obstruction. Then the surgeon selects the optimal calyx for nephrostomy placement, optimization usually being defined by allowing easiest access to the renal calculi and the shortest tract.
Once the calyx is selected, the 0.045 inch diameter deflecting wire guide is inserted through the lumen of the catheter and twist locked to the proximal end of the catheter. Deflection of the wire tip deflects the tip of the catheter, and the catheter and attached wire can be advanced into the selected calyx. However, it is recognized that due to obstructions, e.g. presence of calculi, it may not be possible to advance the catheter into the optimally desired calyx and consequently a less optimal calyx is selected by the surgeon.
After insertion of the catheter into the selected calyx, the deflecting wire guide is removed from the lumen of the catheter, while maintaining the inner-calyx position of the catheter tip. A puncture wire and sheath as a unit are inserted through the catheter lumen, with the puncture wire sharp tip shielded by the sheath. During insertion through the catheter, the wire remains retracted within the sheath, and locked to the sheath by a pin vise lock, so its puncture tip is not exposed. The puncture wire and sheath are connected/locked to the proximal portion of the catheter. The puncture wire is then unlocked from the sheath, by untwisting the cap of the pin vise actuator to loosen the vise pin grip on the puncture wire, and then incrementally advanced from the distal end of the sheath through the flank, fascia and skin. After puncturing the skin, the puncture wire is advanced from below until approximately 15 cm of wire is externally visible.
The pin vise lock securing the puncture wire to the insulating sheath is then re-locked. A fascial incising needle may or may not be passed over the puncture wire at the flank to incise fascia, and is then removed. As the 7 French catheter is advanced through the cystoscope below, the puncture wire is drawn further out of the flank, until the tip of the 7 French catheter is delivered out of the flank. At this time, the 7 French catheter is unlocked from its connection to the puncture wire assembly, and the puncture wire and insulating sheath are removed from below. A 0.038″ guidewire is then passed antegrade through the 7 French catheter from the flank, until it emerges out the lower end of the 7 French catheter at the cystoscope end. With this wire ‘through and through’ the body, the cystoscope and 7 French catheter are removed, leaving the guidewire in place.
The retrograde Lawson approach has several advantages over the antegrade approach including providing the surgeon an anatomic approach to the renal pelvis, increased likelihood of avoiding the interlobar arteries during puncture, and inherently having a wire down the ureter, an important step in securing control over the nephrostomy tract. It is also less skill intensive, due in large part to the fact that it enables travel from the “known kidney” to the “unknown flank/skin,” which better respects the principles of surgery.
However, despite its advantages over the antegrade approach, there are several disadvantages to the Lawson technique. First, although requiring less radiation exposure, the patient is oftentimes still exposed to harmful doses of radiation. Secondly, it is often difficult to navigate the ureteric catheter beyond large obstructive stones in the renal pelvis. This inability to direct the catheter to the desired site (calyx) often leads the surgeon to access a less optimal calyx. Thirdly, fluoroscopy provides only a two dimensional view of the renal anatomy, thereby limiting the ability to confidently select the calyx for tract dilation. Sometimes, there is even uncertainty as to which calyx is actually chosen due to the limited visibility provided by fluoroscopy.
Consequently, it would be advantageous to provide a system and method that enables more precise calyx location, improves access to the calyx of choice, improves visualization, permits “fluoroscopy-free” calyx selection, and allows for preliminary laser lithotripsy of a portion of a stone that may block access to calyx of choice for nephrostomy creation. Also of significance is that nephrostomy tube creation procedures are usually performed by interventional radiologists, which can further compound the risks and problems since urologists usually have better success rates for selecting the calyx for such procedures. Thus, it would be advantageous if such improved system and method could be more commonly performed by urologists.
In an attempt to address some of the disadvantages of the Lawson technique, Dr. Larry C. Munch in an article entitled “Direct-Vision Modified Lawson Retrograde Nephrostomy Technique Using Flexible Ureteroscope” and published in the Journal of EndoUrology, Volume 3, Number 4, 1989, described a technique utilizing a flexible ureteroscope.
In this “Munch technique,” a flexible steerable ureteroscope was utilized to inspect the renal pelvis and calices. As described, a flexible cystoscopy is performed and a 0.035 inch, 145 cm guidewire is passed into the ureteral orifice. Position within the ureter is assessed with fluoroscopy. The cystoscope is removed and a ureteral access sheath with its obturator is advanced over the guidewire, and the obturator is then removed and the ureteroscope is passed through the sheath into the renal pelvis. An appropriate calyx is chosen visually, and then the 0.0017 inch Lawson puncture wire and protective 3Fr radiopaque Teflon sheath is passed through the working channel of the ureteroscope. The calyx is entered and the sheath embedded in the wall of the calyx, and then the pin-vise lock which locks the puncture wire and sheath together is opened and the puncture wire is advanced through the skin under visual and fluoroscopic control. The puncture wire protective sheath and ureteroscope are then withdrawn, leaving the puncture wire and ureteral access sheath in place. At the skin, an 18 gauge needle is passed over the puncture wire into the kidney and then removed. A 9 French fascial dilator is then passed over the 0.017 inch puncture wire into the kidney, whereafter the puncture wire is removed and a 0.038 inch guidewire is passed through the 9 French dilator until it passes down the ureter through the access sheath, and exits through the urethra.
Although the Munch technique solves some of the problems associated with the Lawson technique, it is deficient in several respects. First, the Munch technique leaves the puncture wire exposed to the ureteropelvic junction. This creates the risk of cutting inside tissue, especially at the ureteropelvic junction, across which the very thin puncture wire passes. For example, tension on the puncture wire at the time of passing the antegrade exchange catheter may result in internal ‘slicing’ of the ureteropelvic junction by the thin puncture wire. Second, at the time of deployment of the puncture wire, the Munch technique fails to secure the wire assembly and ureteroscope, forcing either the surgeon or an assistant to devote two hands to opening the pin-vise lock and advancing the puncture wire, all while holding the flexible ureteroscope in position in a selected calyx. This makes wire deployment cumbersome for the surgeon, less likely to be successful, requiring more skilled assistance, and increases the chances the tip of the flexible cystoscope will move out of a selected location for nephrostomy creation. Third, Munch's technique of antegrade wire exchange is ineffectual and risks cutting the puncture wire with passage of 18 gage hollow bore needle over the wire. After passage of this needle, a 9 French fascial dilator is passed over the 0.017″ puncture wire, representing a wire-catheter mismatch which can result in tearing of internal tissues. This large jump from an 18 gauge needle to a 9 French fascial dilator is also cumbersome and has a high chance of failing to grant access to the kidney.
Consequently, it would be advantageous to provide a system and method that would enable urologists to more economically and efficiently perform the nephrostomy procedure to obtain access for nephrostomy tube creation. Such procedure would have the above-noted advantages over the Lawson technique, e.g. improving calyx access, visualization etc., while also providing the advantages of reducing the number of surgical steps and securing the position of the components and protecting the puncture wire, especially at the ureteropelvic junction, thereby providing advantages over the Munch technique.